Method for aligning two objects, method for detecting superimposing state of two objects, and apparatus for aligning two objects

ABSTRACT

Disclosed is a case where an aligning method according to the present invention is applied to a probe apparatus. Target probes are photographed by an upper CCD camera and target electrode pads are photographed by a lower CCD camera. Second virtual images of the photographed probes and first virtual images of the electrode pads are displayed in second and first image data areas on a monitor screen. Dark and light colors in terms of brightness are applied to pixels of the second virtual image and the first virtual image. The second virtual images are moved on the monitor screen, so that the second virtual images are superimposed on the first virtual images. The total sum of the brightness (luminance) of all the first virtual images is calculated. On the basis of the calculated luminance value, a position where the target probes are most successfully brought into contact with the target pads is detected.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based upon and claims the benefit of priorityfrom the prior Japanese Patent Application No. 2000-341265, filed Nov.9, 2000, the entire contents of which are incorporated herein byreference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to a method for aligning twoobjects, a method for detecting a superimposing state of two objects,and an apparatus for aligning two objects. For example, in a probeapparatus, in order to inspect the electric characteristics of an objectto be inspected, it is necessary to allow a plurality of electrodes ofthe inspected object such as a wafer to electrically come into contactwith a plurality of contacts (referred to as probes) of a probe card.The present invention relates to a method for aligning the respectiveelectrodes of the inspected object with the respective contacts torealize the contact.

[0004] 2. Description of the Related Art

[0005] Referring to FIGS. 6A and 6B, for example, the probe apparatuscomprises a loader chamber 1 to/from which a wafer is delivered and aprober chamber 2 in which the electric characteristics of the waferdelivered from the loader chamber 1 is inspected. The loader chamber 1comprises a cassette setting portion 3 on which a cassette C receiving awafer W therein is set, a delivery mechanism (fork) 4 for delivering thewafer W to the loader chamber 1, and a sub chuck 5 for pre-aligning thewafer on the basis of the orientation plane of the wafer while the fork4 delivers the wafer. The prober chamber 2 includes a setting table(hereinbelow, referred to as main chuck) 6 on which the pre-alignedwafer is set and which is moved in X, Y, Z, and θ directions, amechanism (alignment mechanism) 7 for accurately positioning the waferon the main chuck 6, and a probe card 8 having probes 8A. The probe card8 is fixed to a head plate 2A arranged on the top of the prober chamber2.

[0006] As shown in FIGS. 6A and 6B, the alignment mechanism 7 has alower CCD camera 7A and an upper CCD camera 7B. The alignment mechanism7 is controlled by a control device (not shown). The lower CCD camera 7Ais provided for the main chuck 6. The lower CCD camera 7A photographsthe probes 8A of the probe card 8 from the underside. The upper CCDcamera 7B is arranged on the center of an alignment bridge 7C. The upperCCD camera 7B photographs the wafer W on the main chuck 6 from the aboveside. The photographed images of the probes 8A and wafer W are displayedon a monitor screen 9A of a display device 9. The alignment bridge 7C ismoved from the inmost portion (the upper portion in FIG. 6B) of theprober chamber 2 to a probe center along a pair of guide rails 7Darranged in the Y direction in the upper portion of the prober chamber2. The main chuck 6 has a target 7E which is movable above the lower CCDcamera 7A. The optical axis of the lower CCD camera 7A matches theoptical axis of the upper CCD camera 7B through the target 7E. Theposition of the main chuck 6 upon matching is used as a referenceposition for alignment of the wafer W and the probes 8A.

[0007] The prober chamber 2 has a rotatable test head T. The test head Tis electrically connected to the probe card 8 through an interfaceportion (not shown). A signal for inspection is transmitted from atester to electrode pads of the wafer via the test head T and the probes8A.

[0008] The alignment of the probes 8A of the probe card 8 and theelectrode pads of the wafer W will now be described. The upper CCDcamera 7B and the lower CCD camera 7A photograph a plurality of probes8A as targets for alignment (hereinbelow, referred to as target probes)and a plurality of electrode pads corresponding thereto (hereinbelow,referred to as target electrode pads). The optical axis of the upper CCDcamera 7B arranged at the center of the probes is allowed to match theoptical axis of the lower CCD camera 7A fixed to the main chuck throughthe target 7E. The position at that time is set to the referenceposition of the main chuck 6. On the basis of the position coordinatesof each target probe 8A and the reference position coordinates in thephotographing position, the amount of deviation between the target probe8A and the reference position is calculated. Similarly, the amount ofdeviation between each target electrode pad and the reference positionis also calculated. On the basis of the deviation amounts of theplurality of target electrode pads from the reference position, theposition coordinates where the target probes 8A match the target padsare calculated. The main chuck 6 is moved on the basis of thecalculation results to align the target probes 8A with the targetelectrode pads.

[0009] In conventional aligning methods, however, on the basis ofposition data of the target probes 8A, the position data of the targetelectrode pads, and the reference position of the main chuck 6, and theamount to move the main chuck 6 has to be obtained for every targetprobe and every target pad. Accordingly, the calculation process iscomplicated. In association with the super integration of devices, thedesired alignment precision becomes higher. Consequently, thecalculation for alignment becomes more complicated, so that thethroughput of the inspection is deteriorated.

BRIEF SUMMARY OF THE INVENTION

[0010] According to a first aspect of the present invention, there isprovided a method for moving a main chuck on which first objects are setin X, Y, Z, and θ directions to align the first objects with secondobjects arranged above the first objects. The method includes:

[0011] (a) photographing the second objects through second photographingmeans to obtain second photographed images;

[0012] (b) displaying second virtual data images in a second image dataarea on a monitor screen of a display device on the basis of the secondphotographed images of the second objects;

[0013] (c) allowing an optical axis of the second photographing means tomatch an optical axis of first movable photographing means to obtain areference position of the main chuck;

[0014] (d) moving the main chuck to align the first objects with thefirst photographing means and then photographing the first objectsthrough the first photographing means to obtain first photographedimages;

[0015] (e) displaying first virtual data images of the firstphotographed images in a first image data area on the monitor screen ofthe display device on the basis of design data of the first objects;

[0016] (f) relatively moving the first virtual data images and thesecond virtual data images on the monitor screen to superimpose both thevirtual data images on each other; and

[0017] (g) determining a position where both the virtual data images aremost fitly superimposed on each other as an alignment position of thefirst and second objects.

[0018] In the aligning method, preferably, the second photographingmeans is provided for the main chuck.

[0019] In the aligning method, preferably, the first objects are aplurality of electrode pads formed on an object to be inspected and thesecond objects are a plurality of contacts to electrically come intocontact with the electrode pads.

[0020] In the aligning method, preferably, the second virtual dataimages of the contacts in the (b) are displayed with a color having auniform density; in the (d), the electrode pads to be photographed bythe first photographing means are reference electrodes for alignmentamong the plurality of electrode pads formed on the object to beinspected; in the (e), the first virtual data images of the electrodepads are displayed with dark and light colors; and in the (f), aposition where an image density is most changed due to thesuperimposition of the first virtual data image and the second virtualdata image is set to a position where both the virtual data images aresuperimposed on each other so that both the images are most fitlysuperimposed on each other.

[0021] According to a second aspect of the present invention, there isprovided a method for aligning a plurality of electrode pads arranged onan object to be inspected with a plurality of contacts formed on a probecard. The method includes:

[0022] (a) photographing predetermined electrode pads among theelectrode pads through first photographing means to obtain firstphotographed images;

[0023] (b) displaying first virtual data images corresponding to thepredetermined electrode pads in a first image data area on a monitorscreen of a display device on the basis of the first photographed imagesand design data of the predetermined electrode pads,

[0024] the first virtual data images being colored and the colordenoting either of a color having a uniform density and a color having adistributed density;

[0025] (c) photographing the contactors through second photographingmeans to obtain second photographed images;

[0026] (d) displaying second virtual data images of the contactorscorresponding to the second photographed images in a second image dataarea on the monitor screen of the display device,

[0027] the second virtual data images being colored and the colordenoting either of a color having a distributed density and a colorhaving a uniform density;

[0028] (e) relatively moving the first virtual data images and thesecond virtual data images on the monitor screen to superimpose both thevirtual data images on each other and then measuring the luminance ofeach portion where both the virtual data images are superimposed on eachother;

[0029] (f) detecting a superimposing state of the first virtual dataimage and the second virtual data image on the basis of the luminancemeasured in the (e);

[0030] (g) detecting a distance relatively traveled by the virtual dataimages until the superimposition of the first and second virtual dataimages is set to a predetermined state according to the (f); and

[0031] (h) relatively moving the electrode pads and the contactors onthe basis of the traveled distance to align the pads with thecontactors.

[0032] In the aligning method, preferably, the luminance to be measuredis a change in luminance.

[0033] In the aligning method, preferably, in the (f), the superimposingstate of the first and second virtual data images is detected on thebasis of a comparison of the measured luminance with a predeterminedluminance value.

[0034] In the aligning method, preferably, in the (f), the superimposingstate of the first virtual data images and the second virtual dataimages is grasped on the basis of a detection result indicating that themeasured luminance denotes one of a maximum value and a minimum value.

[0035] In the aligning method, preferably, in the (d), each secondvirtual data image formed in the second image data area is one of animage obtained by enlarging a photographed image of each contact and animage obtained by reducing the photographed image.

[0036] In the aligning method, the predetermined electrode pads in the(a) are all of the electrode pads on the object to be inspected, and thecontactors in the (c) are the contactors corresponding to all of theelectrode pads.

[0037] In the aligning method, the predetermined electrode pads amongthe electrode pads in the (a) are reference electrodes for alignment.

[0038] According to a third aspect of the present invention, there isprovided a method for detecting a superimposing state of first objectsand second objects arranged so as to face the first objects. The methodincludes:

[0039] (a) photographing the first objects through first photographingmeans to obtain first photographed images;

[0040] (b) forming first virtual data images corresponding to the firstobjects in a first image data area on a monitor screen of a displaydevice on the basis of the first photographed images and design data ofthe first objects,

[0041] the first virtual data images being colored and the colordenoting either of a color having a uniform density and a color having adistributed density;

[0042] (c) photographing the second objects through second photographingmeans to obtain second photographed images;

[0043] (d) forming second virtual data images corresponding to thesecond objects in a second image data area on the monitor screen of thedisplay device on the basis of the photographed images of the secondobjects,

[0044] the second virtual data images being colored and the colordenoting either of a color having a distributed density and a colorhaving a uniform density;

[0045] (e) relatively moving the first virtual data images and thesecond virtual data images on the monitor screen to superimpose both thevirtual data images on each other and then measuring the luminance ofeach superimposing portion; and

[0046] (f) detecting a superimposing state of the first virtual dataimages and the second virtual data images on the basis of the luminancevalue measured in the (e)

[0047] In the detecting method, preferably, the first objects are aplurality of reference marks arranged in predetermined positions on asubstrate and the second objects are a plurality of contactors formed ona probe card.

[0048] According to a fourth aspect of the present invention, there isprovided a method for moving a main chuck on which a first object is setin X, Y, Z, and θ directions to align the first object with secondobjects arranged above the first object. The method includes:

[0049] (a) photographing the first object;

[0050] (b) photographing the second objects;

[0051] (c) forming image data of the first object on the basis ofphotographing data of the photographed first object;

[0052] (d) forming image data of the second objects on the basis ofphotographing data of the photographed second objects;

[0053] (e) applying dark and light portions to images of the first andsecond image data;

[0054] (f) relatively moving the image data of the first object and theimage data of the second objects, to which the dark and light portionsare applied, to superimpose both images on each other;

[0055] (g) detecting at least one of a position having the lowestluminance and a position having the highest luminance on the basis ofthe luminance of the superimposed images; and

[0056] (h) moving the first object and the second objects on the basisof the detected luminance value to align both the objects with eachother.

[0057] In the aligning method, preferably, the first object is a wafer,the first images are a plurality of electrode pads formed on the wafer,and the second objects are a plurality of probes to be brought intocontact with the electrode pads.

[0058] According to the present invention, there are providedapparatuses corresponding to the methods according to the first, second,third, and fourth aspects of the present invention.

[0059] Other objects and advantages of the present invention will beexplained in the following description in the specification and a partthereof will become apparent from the disclosure or will be obtainedupon employment of the present invention in practice. The objects andadvantages of the present invention will be realized and obtained bycombining means particularly indicated in the description.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

[0060]FIG. 1 is a schematic diagram showing in enlarged dimension astate in which a plurality of probes are come into contact with aplurality of electrode pads;

[0061]FIGS. 2A and 2B show examples of virtual images displayed on imagedata areas on a monitor screen in a process of performing a methodaccording to the present invention, FIG. 2A showing first virtual imagesof first objects (e.g., electrode pads) and FIG. 2B showing secondvirtual images of second objects (e.g., probes of a probe card);

[0062]FIG. 3 shows an example of the monitor screen showing a statewhere dark and light colors (color having distributed densities) areapplied to the virtual images shown in FIGS. 2A and 2B;

[0063]FIG. 4 is a view showing a state where the second virtual imagesof the probes shown in FIG. 3 are moved to be superimposed on the firstvirtual images of the electrode pads;

[0064]FIGS. 5A, 5B, and 5C are explanatory diagrams showing theoperation of an alignment mechanism when an aligning method according tothe present invention is performed, FIG. 5A showing a state where alower CCD camera photographs the probes, FIG. 5B showing a state wherethe optical axis of the lower CCD camera matches the optical axis of anupper CCD camera, and FIG. 5C showing a state where the upper CCD cameraphotographs the electrode pads of a wafer;

[0065]FIGS. 6A and 6B are diagrams showing a probe apparatus, FIG. 6Abeing an exploded front view of the probe apparatus and FIG. 6B being aplan view schematically showing the internal portion of the apparatusshown in FIG. 6A;

[0066] FIGS. 7A-7C show an example of the monitor screen in the secondstate where dark and light colors (colors having distributed densities)are applied to an image, FIG. 7A showing an image of a plurality ofelectrode pads, FIG. 7B showing an image of a plurality of probes, andFIG. 7C illustrating a state where the two images are superimposed oneach other; and

[0067] FIGS. 8A-8C show an example of the monitor screen in the thirdstate where dark and light colors (colors having distributed densities)are applied to an image, FIG. 8A showing an image of a plurality ofelectrode pads, FIG. 8B showing an image of a plurality of probes, andFIG. 8C illustrating a state where the two images are superimposed oneach other.

DETAILED DESCRIPTION OF THE INVENTION

[0068] The present invention relates to a method for aligning twoobjects and a method for detecting a superimposing state of two objects.In order to more specifically explain the present invention, the presentinvention will now be described on the basis of a case where the presentinvention is applied to a probe apparatus capable of being used forinspection of IC chips formed on a semiconductor wafer. The presentinvention is not limited to the applications of the probe apparatus asstipulated in the claims. The “two objects” in the present invention arenot limited to a target electrode pad formed on a semiconductor waferand a target probe of a probe card. The “two objects” include any objectwhich needs to be aligned, for example, an object to be inspected and aninspection part.

[0069] The present invention will now be described on the basis of afirst embodiment shown in FIGS. 1 to 5C. Since the probe apparatus canbe constituted similar to the apparatus shown in FIGS. 6A and 6B, thesame and corresponding portions of the apparatus as those of theapparatus shown in FIGS. 6A and 6B are designated by the same referencenumerals. The aligning method according to the present embodiment can beperformed by using the alignment mechanism 7 controlled by a controldevice (not shown).

[0070] Referring to FIG. 1, first objects (for example, objects to beinspected such as the plurality of electrode pads P of IC chips formedon the semiconductor wafer W) are electrically brought into contact withsecond objects (for example, the plurality of probes 8A of the probecard 8). In the contact state, the electric characteristics of the ICchip(s) on the wafer are inspected.

[0071] In an image processing in the present embodiment, imageprocessing software for alignment can be used. According to the imageprocessing software, on the basis of first photographed images obtainedby photographing the first objects (e.g., electrode pads), secondphotographed images obtained by photographing the second objects (e.g.,contacts), and design data, first virtual images of the electrode padsand second virtual images of the probes can be displayed in first andsecond image data areas on the monitor screen 9A (FIGS. 2A and 2B) ofthe display device 9 (FIG. 6A). According to the image processingsoftware, dark and light colors (color having distributed densities) canbe applied to the first virtual images of the electrode pads and thesecond virtual images of the probes. Furthermore, according to the imageprocessing software, both of the virtual images can be relatively movedon the monitor screen. Due to the relative motion, the virtual imagescan be superimposed on the other virtual images on the monitor screen.Moreover, the image processing software can be constructed so as tocalculate the luminance of the monitor screen, particularly, theluminance in the portion where each virtual image is superimposed on theother virtual image. Further, the image processing software can also beconstructed so that the maximum value or minimum value of the luminancecan be determined.

[0072] The aligning method according to the first embodiment of thepresent invention will now be described. The aligning method accordingto the present embodiment can be controlled by the control device (notshown). For example, as shown in FIG. 5A, the main chuck 6 is moved inthe X and Y directions, so that second image photographing means(hereinbelow, referred to as a “lower CCD camera”) 7A is positionedbelow the probe card 8. The lower CCD camera 7A photographs the probes8A of the probe card 8. According to the present embodiment, forexample, the probes for alignment of the probe card 8 are photographed.As the probes for alignment, for example, three probes located in eachof the four corners of the probe card can be selected. The number ofprobes to be selected is arbitrarily set. All the probes of the probecard can also be selected. The main chuck 6 is moved upward in the Zdirection, so that the lower CCD camera 7A focuses the top ends of thethree probes 8A in each of the four corners. The lower CCD camera 7Aphotographs the top ends of the probes 8A to obtain the secondphotographed images. As shown in FIG. 2B, second virtual images(hereinbelow, referred to as “second virtual images”) 8B of the needlepoints based on the second photographed images are displayed on thesecond image data area of the monitor screen 9A.

[0073] The second photographed image of the needle point of each probe8A has a pin-point size, so it is small. Accordingly, the second virtualimage 8B can be displayed as an image obtained by enlarging the secondphotographed image. When the second photographed image of the probe 8Ais large, it can be displayed in reduced dimension suitable foralignment. On the monitor screen 9A, the X and Y coordinate values aredisplayed in conformity with the position coordinates in the proberchamber 2. The second virtual images 8B are displayed, together with theX and Y coordinates correctly adjusted. In FIG. 2B, the second virtualimages 8B are arranged slightly zigzag. Although it is ideal that theends of the probes are arranged linearly as designed, the ends of theprobes are arranged zigzag under the manufacturing conditions and usingconditions of the probe card.

[0074] The optical axis of the upper CCD camera 7B is allowed to matchthe optical axis of the lower CCD camera 7A as shown in FIG. 5B and thematching position is obtained. In other words, the wafer W received fromthe fork 4 (FIG. 6B) of the loader chamber 1 (FIG. 6A) is set on themain chuck 6. The alignment bridge 7C is moved to the range between themain chuck 6 and the probe card 8 and is then stopped in a probe centerportion below the probe card 8. The target 7E advances over the lowerCCD camera 7A. The lower CCD camera 7A focuses the center of the target7E to recognize a metal thin film. The upper CCD camera 7B focuses thecenter of the target 7E to recognize the metal thin film. According tothe above operation, the optical axis of the lower CCD camera 7A matchesthe optical axis of the upper CCD camera 7B. The intersection of thefocal plane and the optical axis at that time is calculated on the basisof the position of the main chuck 6. The position denotes a referenceposition (X, Y, Z) for alignment and can be registered in a storage unit(not shown). Furthermore, the amount of movement of the main chuck 6 atthat time is detected through, for example, an encoder.

[0075] After that, the center and diameter of the wafer W are obtainedby using the upper CCD camera 7B. The target 7E is moved backward fromthe focal plane of the lower CCD camera 7A. While the main chuck 6 ismoved, the upper CCD camera 7B detects, for example, the predeterminedthree ends on the wafer W. Due to the detection, the distance traveledby the main chuck can be obtained. The center and diameter of the waferW are calculated on the basis of the above detection results. Thecalculation values are registered in the storage unit. Subsequently, theupper CCD camera 7B views a scribing line on the wafer W and alsorotates the wafer W in the θ direction. According to the direction, thedevice formed on the wafer W is aligned with the indexing direction.

[0076] While the main chuck 6 is moved, the upper CCD camera 7Bphotographs the wafer W on the main chuck 6. The photographed image iscompared with a previously registered image in a register device foralignment. As a result of the comparison, the photographed image whichmatches the image in the register device for alignment is extracted.After the photographed image matching the image in the register deviceis extracted, on the basis of design data of the image in the registerdevice, first virtual images P′ of predetermined electrode pads aredisplayed in the first image data area on the monitor screen 9A as shownin FIG. 2A. The displayed predetermined electrode pads can be set to apart or all of the electrode pads on the device. When the design data isnot used, the first virtual images P′ can be also subjected to the sameprocessing as that for the second virtual images of the probes and thendisplayed on the basis of photographing data obtained by photographingthe electrode pads of the corresponding device on the wafer W throughthe CCD camera 7B.

[0077] The arrangement of the first virtual images P′ corresponds to thearrangement of the second virtual images 8B of the probes. Thearrangement of the first virtual images P′ is precisely displayed on thebasis of the reduced X and Y coordinates. As shown in FIGS. 2A and 2B,on the monitor screen 9A, the first image data area in which the firstvirtual images P′ of the electrode pads are displayed and the secondimage data area in which the second virtual images 8B of the probes aredisplayed can be arranged so as to be adjacent to each other in the Xand Y directions. The X and Y coordinate values of the first image dataarea to display the first virtual images P′ and those of the secondimage data area to display the second virtual images 8B can be setdiscontinuously.

[0078] According to the present embodiment, the second virtual images 8Band the first virtual images P′ do not merely denote the probe ends andthe electrode pads. The first and second virtual images can be colored.For example, as shown in FIG. 3, preferably, dark and light colors(color having distributed densities) are applied to the first virtualimages P′. As shown in FIG. 3, a color having a uniform density (e.g.,black that is darkest) can be applied to all the pixels constituting thesecond virtual images 8B of the probes. In the first virtual images P′of the electrode pads, the brightness can be stepwise changed from thecenter to the outside. For example, the first virtual image P′ can beshown in such a manner that the pixels at the center thereof arebrightest, the surrounding pixels are stepwise darkened from the centerto the outside, and the pixels on the outer periphery are darkest. Asfor the colors of the first and second virtual images, the density ofone color can be uniformed and the density of the other color can bedistributed. In consideration of the sizes of the display area of eachfirst virtual image and that of each second virtual image, the colordensity (distribution) can be properly selected.

[0079] Referring to FIG. 3, the second virtual images 8B are displayedby hatching and the first virtual images P′ are displayed withoutgradation.

[0080] According to the present embodiment, as shown in FIG. 3, thesecond virtual images 8B are moved on the monitor screen 9A in thedirection shown by an arrow, so that the second virtual images 8B can besuperimposed on the first virtual images P′. As each of the secondvirtual images 8B is superimposed on each of the first virtual imagesP′, the bright portion of the first virtual image P′ is covered with thesecond virtual image 8B that is black. Consequently, the luminance ofthe first virtual image P′ is stepwise darkened. The luminance can bedetected by calculating the total sum of the brightnesses (luminances)of all of the first virtual images P′. Alternatively, the luminance canbe detected by calculating the total sum of the brightnesses(luminances) in the whole screen of the first image data area.Alternatively, the luminance can be detected by calculating the meanvalue of the luminance of the first virtual image P′ and the luminanceof the peripheral portion.

[0081] A position where each target probe 8A is most successfullyaligned with each target electrode pad P can be grasped as a positionwhere the lowest luminance regarding the first virtual image P′ isobtained. Alternatively, the position where each target probe 8A is mostsuccessfully aligned with each target electrode pad P can be grasped asa position where the luminance of the first virtual image P′ is mostchanged. Alternatively, the position where each target probe 8A is mostsuccessfully aligned with each target electrode pad P can be grasped bydetecting the fact that the luminance regarding the first virtual imageP′ is set to a predetermined value. Alternatively, the position whereeach target probe 8A is most successfully aligned with each targetelectrode pad P can be grasped by detecting the fact that the luminanceregarding the first virtual image P′ is set to the maximum value orminimum value. The most successful alignment of the target probes 8A andthe target pads may also be confirmed by observing the monitor screen 9Awith the unaided eye.

[0082] In order to set each of the target probes 8A and each of thetarget electrode pads P to the most successful contact position, adistance relatively traveled by the second virtual images 8B and thefirst virtual images P′ in the X and Y directions is obtained. Thisdistance corresponds to a distance where the main chuck 6 should bemoved to align the electrode pads with the probes. The distance to bemoved can be registered in the storage unit of the control device.

[0083] The main chuck 6 is moved in the X and Y directions by thedistance to be moved, so that the positions of the electrode pads on thewafer W match the positions of the needle points of the probes 8A. Afterthe positions of the target probes 8A match those of the target pads P,the main chuck 6 is moved so that an object (device) to be firstinspected is located just below the probe card 8. The main chuck 6 ismoved upward in the Z direction and is then overdriven, so that thefirst device is set in a state where the electric characteristicsthereof can be inspected. After the inspection, the main chuck 6 ismoved downward. The indexing of the wafer W is repeated to sequentiallyinspect the devices.

[0084] As described above, according to the first embodiment, the lowerand upper CCD camera 7A and 7B photograph the target probes 8A and thetarget pads P. The first virtual images P′ and the second virtual images8B are displayed in the first and second image data areas on the monitorscreen 9A. The first virtual images P′ and the second virtual images 8Bare colored. The second virtual images 8B or first virtual images P′ aremoved on the monitor screen 9A, so that the virtual images aresuperimposed on the other virtual images. The total sum of thebrightnesses (luminances) of the virtual images is measured. On thebasis of the luminance value, the position where the target probes 8Aare most successfully aligned with the target pads P is grasped. In theabove embodiment, complicated calculations for alignment, which havebeen required so far, are not needed. The target probes 8A can besimultaneously aligned with the corresponding target pads P withoutcomplicated numerical calculation. The alignment situation can bevisually confirmed on the monitor screen 9A. The throughput of theinspection can be raised.

[0085] In the above embodiment, the dark and light colors are applied tothe first virtual images P′ so that the color is stepwise darkened fromthe inside to the outside. The darkening from the outside to the insideis also acceptable. Each second virtual image P′ is colored black. Theimage can be unhatched. Alternatively, dark and light colors can also beapplied to the image. At least two dark and light colors can be used.Various colors including black can be used. The coloring processing ofthe first virtual image P′ and the second virtual image 8B can beperformed in a manner reverse to the above description.

[0086] A second embodiment of the present invention will now bedescribed with reference to FIGS. 7A to 8C. According to the firstembodiment, the color having a uniform density or color havingdistributed densities is applied to the first and second virtual imageson the monitor screen 9A. The second embodiment relates to animprovement of the technique of coloring the virtual image. According tothe second embodiment, the application of the dark and light colors orthe density distribution is changed, so that an arbitrary contact stateof the first and second virtual images can be detected. FIGS. 7A to 7Cshow examples in which first objects denote electrode pads and secondobjects denote probes. FIG. 7A shows virtual images of the electrodepads. FIG. 7B shows virtual images of the probes. The density of a colorapplied to each virtual image shown in FIG. 7A is gradually lowered fromthe left-hand side to the right-hand side. The density is shown as aconcentrically distributing state on the right-hand side. A color havinga uniform high density is applied to the virtual image of each probe inFIG. 7B.

[0087] The virtual images of the electrode pads in FIG. 7A are moved inthe direction toward the virtual images of the probes in FIG. 7B tosuperimpose the images on the other images and the density of theelectrode pad is simultaneously measured. When the highest density isobtained, as shown in FIG. 7C, the virtual images of the probes arealigned with the center portions of the virtual images of the electrodepads, the center portions being located on the right-hand side.

[0088] As mentioned above, the dark and light virtual images shown inFIG. 7A and 7B are used, so that the probes can be aligned with theright-hand side portions of the electrode pads.

[0089] Another example will now be described with reference to FIGS. 8Ato 8C. FIG. 8A shows the virtual images of the electrode pads and FIG.8B shows the virtual images of the probes, respectively. The same darkand light colors as those in FIG. 7A are applied to the virtual imagedrawn in the upper portion in FIG. 8A. A color having distributeddensities obtained by reversing the upper virtual image from left toright is applied to the virtual image drawn in the lower portion in FIG.8B. The upper virtual image shown in FIG. 8B is located on theright-hand side and the lower virtual image is located on the left-handside.

[0090] The virtual images of the electrode pads in FIG. 8A are moved inthe direction toward the virtual images of the probes in FIG. 8B tosuperimpose the virtual images on the other virtual images and thedensity of each electrode pad is simultaneously measured. When thehighest density is obtained, as shown in FIG. 8C, the virtual images ofthe probes are aligned with the center portions of the virtual images ofthe electrode pads, the center portions being located on the right-handside.

[0091] As mentioned above, when the dark and light virtual images shownin FIG. 8A are used, it is possible to align the probes, which aredesigned so that the probes are brought into contact with the electrodepads in the different positions as shown in FIG. 8B, with thepredetermined electrode pads.

[0092] A third embodiment of the present invention will now bedescribed. The present embodiment relates to a method for detecting thesuperimposing state of the first and second objects. As in the firstembodiment, the second virtual images 8B are moved in the directionshown by the arrow on the monitor screen 9A to superimpose the secondvirtual images on the first virtual images. As the second virtual images8B are superimposed on the first virtual images P′, the bright portionof each first virtual image P′ is covered with the second virtual image8B which is black. Consequently, the luminance of the first virtualimage P′ is stepwise darkened. The luminance is changed in accordancewith the degree of superimposition of the first and second virtualimages. The third embodiment relates to a method for detecting thesuperimposing state of the two objects on the basis of the luminancevalue. Similar to the first embodiment, the luminance can be detected bycalculating the brightness (luminance) of the portion where both thevirtual images are superimposed on each other on the monitor screen.

[0093] A fourth embodiment relates to a method for inspecting whetherall the probes of the probe card are arranged in the correct positionsby using the method according to the third embodiment. In other words,in the fourth embodiment, the first objects are set to a plurality ofreference marks arranged in predetermined positions on a substrate andthe second objects are set to a plurality of probes of the probe card.In the fourth embodiment, the second virtual images of the probes aresuperimposed on the first virtual images of the reference marks. Thesuperimposing state can be grasped by measuring the luminance of thesuperimposing portion. For example, when the probes include a probearranged in a position deviated from the predetermined position, themeasured luminance denotes a value that is different from the essentialluminance value. As mentioned above, when the luminance is measured, thepresence or absence of the probe, which is located in the positiondeviated from the predetermined position, among the probes can bedetected.

[0094] In the above embodiments, the case where the present inventionwas applied to the alignment in the probe apparatus has been described.However, the present invention can also be applied to the other aligningmethods. In this case, the shapes of the first and second objects can beset according to the respective objects and design data.

What is claimed is:
 1. A method for moving a main chuck on which firstobjects are set in X, Y, Z, and θ directions to align the first objectswith second objects arranged above the first objects, the methodcomprising: (a) photographing the second objects through secondphotographing means to obtain second photographed images; (b) displayingsecond virtual data images in a second image data area on a monitorscreen of a display device on the basis of the second photographedimages of the second objects; (c) allowing an optical axis of the secondphotographing means to match an optical axis of first movablephotographing means to obtain a reference position of the main chuck;(d) moving the main chuck to align the first objects with the firstphotographing means and then photographing the first objects through thefirst photographing means to obtain first photographed images; (e)displaying first virtual data images of the first photographed images ina first image data area on the monitor screen of the display device onthe basis of design data of the first objects; (f) relatively moving thefirst virtual data images and the second virtual data images on themonitor screen to superimpose both the virtual data images on eachother; and (g) determining a position where both the virtual data imagesare most fitly superimposed on each other as an alignment position ofthe first and second objects.
 2. The method according to claim 1,wherein the second photographing means is provided for the main chuck.3. The method according to claim 1, wherein the first objects are aplurality of electrode pads formed on an object to be inspected and thesecond objects are a plurality of contactors to be electrically broughtinto contact with the electrode pads.
 4. The method according to claim3, wherein in (b), the second virtual data images of the contactors aredisplayed with a color having a uniform density, in (d), the electrodepads to be photographed by the first photographing means are referenceelectrodes for alignment among the plurality of electrode pads formed onthe object to be inspected, in (e), the first virtual data images of theelectrode pads are displayed with dark and light colors, and in (f), aposition where an image density is most changed due to thesuperimposition of the first virtual data image and the second virtualdata image is set to a position where both the virtual data images aresuperimposed on each other so that both the images are most fitlysuperimposed on each other.
 5. A method for aligning a plurality ofelectrode pads arranged on an object to be inspected with a plurality ofcontacts formed on a probe card, the method comprising: (a)photographing predetermined electrode pads among the electrode padsthrough first photographing means to obtain first photographed images;(b) displaying first virtual data images corresponding to thepredetermined electrode pads in a first image data area on a monitorscreen of a display device on the basis of the first photographed imagesand design data of the predetermined electrode pads, the first virtualdata images being colored and the color denoting either of a colorhaving a uniform density and a color having a distributed density; (c)photographing the contactors through second photographing means toobtain second photographed images; (d) displaying second virtual dataimages of the contactors corresponding to the second photographed imagesin a second image data area on the monitor screen of the display device,the second virtual data images being colored and the color denotingeither of a color having a distributed density and a color having auniform density; (e) relatively moving the first virtual data images andthe second virtual data images on the monitor screen to superimpose boththe virtual data images on each other and then measuring the luminanceof each portion where both the virtual data images are superimposed oneach other; (f) detecting a superimposing state of the first virtualdata image and the second virtual data image on the basis of theluminance measured in the (e); (g) detecting a distance relativelytraveled by both the virtual data images until the superimposition ofthe first virtual data images and the second virtual data images is setto a predetermined state according to (f); and (h) relatively moving theelectrode pads and the contactors on the basis of the traveled distanceto align the pads with the contactors.
 6. The method according to claim5, wherein in (e), the luminance to be measured is a change inluminance.
 7. The method according to claim 5, wherein in (f), thesuperimposing state of the first virtual data images and second virtualdata images is detected on the basis of a comparison of the measuredluminance with a predetermined luminance value.
 8. The method accordingto claim 5, wherein in (f), the superimposing state of the first virtualdata images and the second virtual data images is grasped on the basisof a detection result indicating that the measured luminance denotes oneof a maximum value and a minimum value.
 9. The method according to claim5, wherein in (d), each second virtual data image formed in the secondimage data area is one of an image obtained by enlarging a photographedimage of each contactor and an image obtained by reducing thephotographed image.
 10. The method according to claim 5, wherein thepredetermined electrode pads in (a) are all of the electrode pads on theobject to be inspected, and the contactors in (c) are the contactorscorresponding to all of the electrode pads.
 11. The method according toclaim 5, wherein the predetermined electrode pads among the electrodepads in (a) are reference electrodes for alignment.
 12. A method fordetecting a superimposing state of first objects and second objectsarranged so as to face the first objects, the method comprising: (a)photographing the first objects through first photographing means toobtain first photographed images; (b) forming first virtual data imagescorresponding to the first objects in a first image data area on amonitor screen of a display device on the basis of the firstphotographed images and design data of the first objects, the firstvirtual data images being colored and the color denoting either of acolor having a uniform density and a color having a distributed density;(c) photographing the second objects through second photographing meansto obtain second photographed images; (d) forming second virtual dataimages corresponding to the second objects in a second image data areaon the monitor screen of the display device on the basis of thephotographed images of the second objects, the second virtual dataimages being colored and the color denoting either of a color having adistributed density and a color having a uniform density; (e) relativelymoving the first virtual data images and the second virtual data imageson the monitor screen to superimpose both the virtual data images oneach other and then measuring the luminance of each superimposingportion; and (f) detecting a superimposing state of the first virtualdata images and the second virtual data images on the basis of theluminance value measured in the (e).
 13. The method according to claim12, wherein the first objects are a plurality of reference marksarranged in predetermined positions on a substrate and the secondobjects are a plurality of contact formed on a probe card.
 14. Anapparatus for moving a main chuck on which first objects are set in X,Y, Z, and θ directions to align the first objects with second objectsarranged above the first objects, the apparatus comprising: secondphotographing means for photographing the second objects to obtainsecond photographed images; means for displaying second virtual dataimages in a second image data area on a monitor screen of a displaydevice on the basis of the second photographed images of the secondobjects; means for allowing an optical axis of the second photographingmeans to match an optical axis of first movable photographing means toobtain a reference position of the main chuck; means for moving the mainchuck to align the first objects with the first photographing means andthen allowing the first photographing means to photograph the firstobjects to obtain first photographed images; means for displaying firstvirtual data images of the first photographed images in a first imagedata area on the monitor screen of the display device on the basis ofdesign data of the first objects; means for relatively moving the firstvirtual data images and second virtual data images on the monitor screento superimpose both the virtual data images on each other; and means fordetermining a position where both the virtual data images are most fitlysuperimposed on each other as an alignment position of the first andsecond objects.
 15. The apparatus according to claim 14, wherein thesecond photographing means is provided for the main chuck.
 16. Theapparatus according to claim 14, wherein the first objects are aplurality of electrode pads formed on an object to be inspected and thesecond objects are a plurality of contacts to be electrically broughtinto contact with the electrode pads.
 17. The apparatus according toclaim 16, wherein the second virtual data images are displayed with acolor having a uniform density, the electrode pads photographed by thefirst photographing means are reference electrodes for alignment amongthe electrode pads formed on the object to be inspected, the firstvirtual data images of the electrode pads are displayed with dark andlight colors, and the superimposing means determines a position where animage density is most changed due to the superimposition of the firstvirtual data images and the second virtual data images as a positionwhere both the virtual data images are superimposed on each other sothat both the images are most fitly superimposed on each other.
 18. Anapparatus for aligning a plurality of electrode pads arranged on anobject to be inspected with a plurality of contactors formed on a probecard, the apparatus comprising: first photographing means forphotographing predetermined electrode pads among the electrode pads toobtain first photographed images; means for displaying first virtualdata images corresponding to the predetermined electrode pads in a firstimage data area on a monitor screen of a display device on the basis ofthe first photographed images and design data of the predeterminedelectrode pads, the first virtual data images being colored and thecolor denoting either of a color having a uniform density and a colorhaving a distributed density; second photographing means forphotographing the contactors to obtain second photographed images; meansfor displaying second virtual data images of the contactorscorresponding to the second photographed images in a second image dataarea on the monitor screen of the display device, the second virtualdata images being colored and the color denoting either of a colorhaving a distributed density and a color having a uniform density; meansfor relatively moving the first virtual data images and the secondvirtual data images on the monitor screen to superimpose both thevirtual data images on each other and then measuring the luminance of aportion where both the virtual data images are superimposed on eachother; means for detecting a superimposing state of the first virtualdata images and the second virtual data images on the basis of themeasured luminance; means for detecting a distance relatively traveledby both the virtual data images until the superimposition of the firstvirtual data images and the second virtual data images is set to apredetermined state by the means for detecting the superimposing state;and means for relatively moving the electrode pads and the contactors onthe basis of the traveled distance to align the pads with thecontactors.
 19. The apparatus according to claim 18, wherein theluminance measured by the means for measuring the luminance is a changein luminance.
 20. The apparatus according to claim 18, wherein the meansfor detecting the superimposing state detects the superimposing state onthe basis of a comparison of the measured luminance with a predeterminedluminance value.
 21. The apparatus according to claim 18, wherein themeans for detecting the superimposing state grasps the superimposingstate of the first virtual data images and the second virtual dataimages on the basis of a detection result indicating that the measuredluminance denotes one of a maximum value and a minimum value.
 22. Theapparatus according to claim 18, wherein each second virtual data imageformed in the second image data area through the displaying means is oneof an image obtained by enlarging a photographed image of each contactorand an image obtained by reducing the photographed image.
 23. Theapparatus according to claim 18, wherein the predetermined electrodepads photographed by the first photographing means are all of theelectrode pads on the object to be inspected, and the contactorsphotographed by the second photographing means are the contactorscorresponding to all of the electrode pads.
 24. The apparatus accordingto claim 18, wherein the electrode pads photographed by the firstphotographing means are reference electrodes for alignment.
 25. Anapparatus for detecting a superimposing state of first objects andsecond objects arranged so as to face the first objects, the apparatuscomprising: first photographing means for photographing the firstobjects to obtain first photographed images; means for forming firstvirtual data images corresponding to the first objects in a first imagedata area on a monitor screen of a display device on the basis of thefirst photographed images and design data of the first objects, thefirst virtual data images being colored and the color denoting either ofa color having a uniform density and a color having a distributeddensity; second photographing means for photographing the second objectsto obtain second photographed images; means for forming second virtualdata images corresponding to the second objects in a second image dataarea on the monitor screen of the display device on the basis of thephotographed images of the second objects, the second virtual dataimages being colored and the color denoting either of a color having adistributed density and a color having a uniform density; means forrelatively moving the first virtual data images and the second virtualdata images on the monitor screen to superimpose both the virtual dataimages on each other and then measuring the luminance of eachsuperimposing portion; and means for detecting a superimposing state ofthe first virtual data images and the second virtual data images on thebasis of the measured luminance value.
 26. The apparatus according toclaim 25, wherein the first objects are a plurality of reference marksarranged in predetermined positions on a substrate and the secondobjects are a plurality of contacts formed on a probe card.
 27. Anapparatus for moving a main chuck on which a first object is set in X,Y, Z, and θ directions to align the first object with second objectsarranged above the first object, the apparatus comprising: firstphotographing means for photographing the first object; secondphotographing means for photographing the second objects; first imageforming means for forming image data of the first object on the basis ofdata obtained by the first photographing means; second image formingmeans for forming image data of the second objects on the basis of dataobtained by the second photographing means; dark and light portionsapplying means for applying dark and light portions to the image dataformed by the first and second image forming means; means for relativelymoving the image data of the first object and the image data of thesecond objects, to which the dark and light portions are applied by thedark and light portions applying means, to superimpose both the imageson each other; luminance detecting means for detecting at least one of aposition having the lowest luminance and a position having the highestluminance on the basis of the luminance of the images superimposed bythe superimposing means; and aligning means for aligning the firstobject with the second objects by moving both the objects on the basisof the detection result obtained by the luminance detecting means. 28.The apparatus according to claim 27, wherein the first object is awafer, first images are a plurality of electrode pads formed on thewafer, and the second objects are a plurality of probes to be come intocontact with the electrode pads.
 29. A method for moving a main chuck onwhich a first object is set in X, Y, Z, and θ directions to align thefirst object with second objects arranged above the first object, themethod comprising: (a) photographing the first object; (b) photographingthe second objects; (c) forming image data of the first object on thebasis of photographing data of the photographed first object; (d)forming image data of the second objects on the basis of photographingdata of the photographed second objects; (e) applying dark and lightportions to images of the first and second image data; (f) relativelymoving the image data of the first object and the image data of thesecond objects, to which the dark and light portions are applied, tosuperimpose both images on each other; (g) detecting at least one of aposition having the lowest luminance and a position having the highestluminance on the basis of the luminance of the superimposed images; and(h) moving the first object and the second objects on the basis of thedetected luminance value to align both the objects with each other. 30.The method according to claim 29, wherein the first object is a wafer,the first images are a plurality of electrode pads formed on the wafer,and the second objects are a plurality of probes to be come into contactwith the electrode pads.